Chemically amplified negative photoresist, and photoresist composition

ABSTRACT

A polymer for a chemically amplified negative photoresist and a photoresist composition are provided. A representative polymer of the invention is a compound of formula 5:  
                 
 
     wherein:  
     R 1  is H or CH 3 ;  
     R 2  and R 4  are each independently (R) α (CH 2 ) β R′ or (R) α [(CH 2 ) γ O] δ R′ (wherein, R is CO, CO 2 , O, OCO, or OCO 2 , R′ is O, CO 2 , or OCO 2 , α is 0 or 1, β is 0 to 5, γ is 1 or 2, and δ is 1 to 5);  
     R 3  is represented by one of the formula:  
                 
 
     wherein R 6 , which combines an acetal compound and a vinyl compound, is a C 1 -C 5  saturated alkyl, a C 1 -C 5  ether, or a C 1 -C 5  carbonyl; R 7  to R 11  are each independently selected from H, C 1 -C 5  saturated alkyls, C 1 -C 5  ethers, C 1 -C 5  carbonyl groups, and C 1 -C 5  alcohol groups; and m is a number ranging from 1-5; and  
     R 5  is represented by formula:  
                 
 
     wherein R 12  and R 13  are each independently H or OH; and  
     * represents the bonding site at which the R 4  group is bonded.  
     R 14  and R 16  are each independently selected from a single bond (R) α (CH 2 ) β R′ and (R) α [(CH 2 ) γ O] δ R′ (wherein, R is CO, CO 2 , O, OCO, or OCO 2 , R′ is O, CO 2 , or OCO 2 , α is 0 or 1, β is 0 to 5, γ is 1 or 2, and δis 1 to 5); R 15  is a hydroxyl group; R 17  is a carboxyl group;  
     a, b, c, and d represent the mole ratios of each monomer, wherein a has a value of 0-0.5, b has a value of 0-0.9, c has a value of 0-0.3, and d has a value of 0-0.3, provided that a+b+c+d=1; and  
     n represents the degree of polymerization of each polymer, and has a value of at least 2.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is based on application No. 2001-17601 filed inthe Korean Industrial Property Office on Apr. 3, 2001, the disclosure ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to a polymer for a chemicallyamplified negative photoresist, and a photoresist composition. Moreparticularly, this invention relates to a chemically amplified negativephotoresist composition which enables the formation of high resolutionpatterns.

BACKGROUND OF THE INVENTION

[0003] Photoresist compositions are used for the formation of circuitpatterns such as circuits of liquid crystal display devices orsemiconductor integrated circuits. Conventionally, novolak-based resinswhich are alkai-soluble phenol-(or cresol-) formaldehyde resins, andnaphthoquinonediazido-based compounds as photosensitive materials arewidely used in photoresist compositions, as disclosed in U.S. Pat. Nos.3,666,473, 4,115,128, and 4,173,470.

[0004] Recently, along with increasing requirements of finemicro-circuit patterns, the wavelengths of KrF (248 nm) and ArF excimerlaser (193 nm) are used for the formation of circuit patterns. At thesewavelengths the novolak-based resins and naphthoquinonediazo-basedcompounds lose their applicability due to their poor sensitivity andstrong absorption at 248 and 193 nm. Consequently, there is a demand forthe development of a novel photoresist resin that can be usedeffectively at the above wavelengths.

[0005] It is essential for a novel photoresist resin to satisfy variousrequirements such as high sensitivity, high resolution, and highresistance against dry etching. Among those requirements, sensitivity isthe most important property. As a solution to enhance sensitivity, theconcept of chemical amplification has been introduced in this field oftechnology.

[0006] In the chemical amplification process, an active speciesgenerated by a photochemical reaction acts as a catalyst which promotesa continuous reaction of deprotection, crosslinking, and the like. As aresult, the total quantum yield is amplified to a much higher level witha small amount of the active species. In this manner, a highly-sensitivephotoresist is provided. Recently, chemically amplified photoresistshave been increasingly highlighted in photolithographic processes forsemiconductor production in order to achieve high photosensitivity.Chemically amplified photoresist compositions contain photoresist resinshaving acid-sensitive reactivity, photoacid generators, and organicsolvents as a mixing medium for other components.

[0007] The reaction mechanism of chemically amplified photoresists issuch that photoacid generators generate strong protonic acids when theyare exposed to light and these acids cause an acid-catalysis reaction ofthe photoresist resins to proceed. At this stage, a deprotectionreaction is preformed for a positive photoresist composition, whereas acrosslinking reaction is performed in the case of a negativephotoresist. As a result of such a reaction, the exposed portion shows adifferent solubility in a developing agent than the unexposed portion,and can be utilized in patterning process. As an example of thesechemically amplified photoresists, a compound of polyvinylphenol resinprotected by a t-butoxycarbonyl group-photoacid generator is disclosedin U.S. Pat. Nos. 4,311,782, 4,405,708, and 4,491,628. The ArF excimerlaser lithography is expected to be the most promising lithographymethod for manufacturing of 1 Gbit or more DRAMs of semiconductor chips.However, since aromatic compounds in the polyvinylphenol give lowphotosensitivity due to strong absorption at a wavelength of 193 nm, itis only applicable at a wavelength of 248 nm or higher.

[0008] Under these circumstances, in order to develop a photoresistresin having high transmittance at a wavelength of 193 nm, and with highresolution as well as high resistance against dry etching, an aliphaticcyclic compound-included chemically amplified photoresist has beenconsidered. For example, there has been reported in U.S. Pat. Nos.5,585,223, 5,691,111, and 5,756,850 a compound with an alicycliccompound bonded on a (meth)acrylic side chain or a (meth)acrylic polymerhaving an alicyclic compound as a dissolution inhibitor. Another type ofcompound with an alicyclic compound composed of a polymeric main chainby means of copolymerization of norbornene monomers and maleic anhydridehas also been reported in U.S. Pat. No. 6,028,153.

[0009] For a chemically amplified negative photoresist using a photoacidgenerator, U.S. Pat. Nos. 6,106,998, 6,074,801, and 5,955,241 disclose aprocess using an epoxy group or an alkoxymethylamide group as acrosslinking functional group. However, there is still an unsatisfactorylevel of resolution due to the occurrence of swelling during thedeveloping process.

SUMMARY OF THE INVENTION

[0010] An object of the present invention is to provide a monomer for achemically amplified negative photoresist useful for the preparing achemically amplified negative photoresist polymer that does not causeproblems such as swelling.

[0011] Another object of the present invention is to provide a polymerfor a chemically amplified negative photoresist prepared with themonomer.

[0012] Still another object of the present invention is to provide achemically amplified negative photoresist composition including thepolymer, which enables forming a pattern of high resolution.

[0013] In order to achieve these objects, the present invention providesa monomer for a chemically amplified negative photoresist represented byFormula 1 or 2:

[0014] wherein,

[0015] R₁ is H or CH₃;

[0016] R₂ and R₄ are each independently selected from (R)_(α)(CH₂)_(β)R′and (R)_(α)[(CH₂)_(γ)O]_(δ)R′ (wherein, R is CO, CO₂, O, OCO, or OCO₂,R′ is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1 or 2, and δ is 1to 5);

[0017] R₃ is selected from:

[0018] wherein R₆, which combines an acetal compound and a vinylcompound, is a C₁-C₅ saturated alkyl, a C₁-C₅ ether, or a C₁-C₅carbonyl; R₇ to R₁₁ are each independently selected from H, C₁-C₅saturated alkyls, C₁-C₅ ethers, C₁-C₅ carbonyl groups, and C₁-C₅ alcoholgroups; and m is a number ranging from 1-5, and

[0019] R₅ is represented by the formula:

[0020] wherein, R₁₂ and R₁₃ are each independently selected from H andOH;

[0021] and * represents a bonding site at which the R₄ group is bonded.

[0022] The present invention further provides a polymer for a chemicallyamplified negative photoresist represented by formula 5:

[0023] wherein:

[0024] R₁ is H or CH₃;

[0025] R₂ and R₄ are each independently selected from (R)_(α)(CH₂)_(β)R′and (R)_(α)[(CH₂)_(γ)O]_(δ)R′ (wherein, R is CO, CO₂, O, OCO, or OCO₂,R′ is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1 or 2, and δ is 1to 5);

[0026] R₃ is selected from:

[0027] wherein R₆, which combines an acetal compound and a vinylcompound, is a C₁-C₅ saturated alkyl, a C₁-C₅ ether, or a C₁-C₅carbonyl; R₇ to R₁₁ are each independently selected from H, C₁-C₅saturated alkyls, C₁-C₅ ethers, C₁-C₅ carbonyl groups, and C₁-C₅ alcoholgroups; and m is a number ranging from 1-5,

[0028] R₅ is represented by the following formula:

[0029] wherein R₁₂ and R₁₃ are each independently selected from H andOH;

[0030] and * represents a bonding site at which the R₄ group is bonded;

[0031] R₁₄ and R₁₆ are each independently selected from a single bond,(R)_(α)(CH₂)_(β)R′ and (R)_(α)[(CH₂)_(γ)O]₆₇ R′ (wherein, R is CO, CO₂,O, OCO, or OCO₂, R′ is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1or 2, and δ is 1 to 5); R₁₅ is a hydroxyl group; R₁₇ is a one havingcarboxyl group;

[0032] a, b, c, and d represent the mole ratios of the correspondingmonomers, a has a value of 0-0.5, b has a value of 0-0.9, c has a valueof 0-0.3, and d has a value of 0-0.3, provided that a+b+c+d=1; and

[0033] n represents the degree of polymerization of each polymer, andhas a value of at least 2, and preferably 2 to 100,000.

[0034] The present invention further provides a chemically amplifiednegative photoresist composition including the polymer and a photoacidgenerator.

DETAILED DESCRIPTION OF THE INVENTION

[0035] The present invention relates to a polymer that is useful for achemically amplified negative photoresist composition that is used in aphotolithographic process with a light source of ultraviolet or deepultraviolet radiation for the formation of micro-patterns ofsemiconductor devices. A representative polymer for the above polymer isa compound of formula 5:

[0036] wherein R₁, R₂, R₃, R₄, R₅, R₁₄, R₁₅, R₁₆, R₁₇, a, b, c, d, and nare the same as defined above.

[0037] The acetal group included in the polymer of formula 5 functionsas a site where a crosslinking reaction occurs when it is heated in thepresence of an acid, and the bile acid derivative of formula 5 functionsto provide a hydroxyl group participating in the crosslinking reactionand to increase resistance against dry etching by alicyclic rings.

[0038] The polymer represented by the formula 5 can be formed by thepolymerization of monomers of the formulas 1 to 4:

[0039] wherein, R₁ to R₅, R₁₄ to R₁₇ are the same as defined above.

[0040] The compound of formula 1 may be prepared by reacting an alcoholcontaining an acetal group with a vinyl compound. The alcohol containingan acetal group may be prepared by reacting aldehydes with triolcompounds. An example of the preparation method is one in whichaldehydes and glycerols are mixed with petroleum ether, benzene, ortoluene, which forms an azeotropic mixture, and the mixture is heated inthe presence of an acid, such as p-toluenesulfonic acid, and refluxed.Water generated during the reaction is removed by dean a starkapparatus. Then the resultant primary alcohol containing an acetal groupis reacted with a vinyl compound, such as (meth)acryoylchloride, wherebya vinyl-based monomer of formula 1 is obtained.

[0041] Examples of the aldehydes include acetaldehyde, isobutylaldehyde,butylaldehyde, 2-methylbutylaldehyde, 2-ethylbutylaldehyde,valeraldehyde, isovaleraldehyde, 3,3-dimethylbutylaldehyde,2-methylvaleraldehyde, and 2,3-dimethylvaleraldehyde. Since theabove-mentioned reactions of acetal and vinyl compounds and of aldehydesand glycerols are well known in the art, a detailed description thereofis omitted in this specification.

[0042] Alternatively, the monomer of the formula 1 may be prepared byreacting sodium acrylate or potassium acrylate with bromoacetaldehyde,2-(2-bromomethyl)-1,3-dioxolane, or 2-(2-bromoethyl)-1,3-dioxane.

[0043] The homopolymer or copolymer prepared by polymerizing monomers ofthe formula 1 or 2 may be used as the photoresist polymer. In the caseof using the homopolymer, it is preferable to use a blend of twodifferent homopolymers, and the mixing ratio of the homopolymers may beproperly adjusted according to the desired properties of the product.

[0044] The homopolymer may be represented by the following formula 6 or7:

[0045] wherein R₁ to R₅ and n are the same as defined above.

[0046] The homopolymer of formula 6 can be prepared by polymerizing themonomer of formula 1, and the homopolymer of formula 7 can be preparedby polymerizing the monomer of formula 2. Any of the conventionalmethods to produce polymers can be utilized as the polymerizationprocess for the present invention, and a radical polymerization processwill be described below.

[0047] The monomer of formula 1 is dissolved in a solvent such astetrahydrofuran, and an initiator for radical polymerization, such as2,2′-azobisisobutyronitrile, is added to the solution, the reactionresulting in the polymer of formula 6.

[0048] In addition, a copolymer of formula 5 and a homopolymer offormula 6 or 7 may be used as a photoresist polymer for the presentinvention.

[0049] wherein R₁ to R₅, R₁₄ to R₁₇, a, b, c, d and n are the same asdefined above.

[0050] In the formula 5, the monomer having a hydroxyl functional groupacts as a controller of the degree of crosslinking, and the monomerhaving a carboxyl functional group controls photosensitivity anddeveloping capability.

[0051] A photoresist composition according to the present inventionincludes as a photoresist resin a homopolymer of the formula 6 or 7, ora mixture thereof, and preferably a blend of the homopolymers.Alternatively, the photoresist composition includes a copolymer of theformula 5. In addition, the photoresist composition includes a photoacidgenerator. In the photoresist composition, the content of polymer as thephotoresist resin ranges from 10 to 20 wt. % based on photoresist, andthe content of the photoacid generator preferably ranges from 1 to 5 wt.% of the polymer. If the content of polymer is less than 10 wt. %,either the film will be too thin or formation of the film will beinsufficient, whereas if the content of polymer exceeds 20 wt. %, itwill be difficult to obtain a uniform film due to an increase in theviscosity of the photoresist.

[0052] As for the photoacid generator, if the content is less than 1 wt.% of the polymer, a deficiency of the amount of acid generated will leadto insufficient crosslinking, while if the content exceeds 5 wt. %,photosensitivity will be decreased due to the increased UV absorption bythe photoacid generator itself.

[0053] The photoacid generator produces acid when it is exposed to UVlight. The acid thus generated will activate an alcohol group of thepolymer to attack an acetal group, and thereby promotes a crosslinkingreaction. As the photoacid generator, any conventionally known compoundcapable of generating an acid by the irradiation of UV light can be usedwithout any special limitation. Examples of such a photoacid generatorinclude one or more sulfonium salts or onium salts, such asdiphenyliodonium hexafluorophosphate, diphenyliodoniumhexafluoroarsenate, diphenyliodonium hexafluoroantimonate,diphenylparaisobutylphenyl triplate, diphenylparatoluenyl triplate,diphenylpara-t-butylphenyl triplate, triphenylfulfoniumhexafluorophosphate, triphenylsulfonium hexafluoroarsenate,triphenylsulfonium hexafluoroantimonate, triphenylsulfonium triplate, ordibutylnaphthylsulfonium triplate.

[0054] The photoresist composition according to the present inventionincludes an organic solvent. As the organic solvent, cyclohexanone,methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propylene glycolmonomethylether acetate, or other general organic solvent can be used.

[0055] The photoresist composition according to the present invention isactivated when it is heated in the presence of an acid, such that anucleophilic functional group, such as a hydroxyl or carboxyl group,attacks an acetal group to result in a crosslinking reaction. Acid isgenerated when the photoacid generator is irradiated by light, and thecrosslinking reaction in the presence of an acid proceeds in achemically amplified manner, so that photosensitivity is enhanced and noswelling occurs due to the increased degree of crosslinking.

[0056] A method of pattern formation using the photoresist compositionaccording to the present invention is described below.

[0057] A photoresist resin and a photoacid generator are dissolved in anorganic solvent, and then the solution is selectively filtered with afilter to produce a photoresist. The obtained photoresist is coated ontoa silicon wafer. The method of coating includes any conventionally knownprocesses, a typical example being a spin-coating process. Subsequently,the wafer is pretreated (soft-baked) in an oven or a hot-plate at90-150° C. for 60-120 seconds, and the resultant product is thensubjected to irradiation using a UV or excimer laser exposure tools. Theexposed wafer is subjected to post-treatment (post-bake) in an oven or ahot-plate at 90-150° C. for 60-120 seconds. The post-baked wafer isdipped into a developing solution for a predetermined period to form aphotoresist pattern. The developing solution includes at least onecomposition selected from aqueous solutions of tetramethylammoniumhydroxide, potassium hydroxide, potassium carbonate, sodium phosphate,sodium silicate, and ammonia water or an alkali solution of an aqueousamine.

[0058] The following examples illustrate the present invention infurther detail, but the present invention is not limited by theseexamples.

EXAMPLE 1

[0059]0.5 mol of sodium acrylate and 0.4 mol of bromoacetaldehydediethylacetal were dissolved in dimethyl sulfate, and the solution wasstirred at a temperature of 35° C. for 10 hours. The reactiontemperature was cooled to ambient temperature, and then the product wasseparated from the reaction mixture by using water and ethyl ether.After the product was concentrated by means of a vacuum evaporator, theconcentrate was subjected to vacuum distillation to yield a compound offormula 8:

EXAMPLE 2

[0060] A compound of formula 9 was prepared by the same procedure as inExample 1 except that 2-(2-bromoethyl)-1,3-dioxolane was used instead ofbromoacetaldehyde diethylacetal

EXAMPLE 3

[0061] A compound of formula 10 was prepared by the same procedure as inExample 1 except that 2-(2-bromoethyl)-1,3-dioxane was used instead ofbromoacetaldehyde diethylacetal.

EXAMPLE 4

[0062]0.2 mol of butylaldehyde, 0.26 mol of glycerol, and a trace amountof p-toluene sulfonic acid were dissolved in petroleum ether, and thesolution was heated to reflux for 6 hours in a reactor equipped with adean stark apparatus to terminate the reaction. Then the product wasextracted from the reaction mixture by using water and ethyl ether. Theobtained extract was subjected to fractional distillation to yield apure primary alcoholic compound with an acetal group.

[0063] 0.15 mol of the primary alcoholic compound and 0.2 mol oftriethylamine were dissolved in purified tetrahydrofuran, then 0.17 molof acryloyl chloride was slowly added to the solution using a droppingfunnel, and the reactants were stirred at ambient temperature for 6hours. After the reaction ended, amine salt produced during the reactionwas removed using a glass filter, and the reaction mass was processed byvacuum distillation to yield a compound of formula 11:

EXAMPLE 5

[0064] A compound of formula 12 was prepared by the same procedure as inExample 4 except that 2-(hydroxymethyl)-1,3-propandiol was used insteadof glycerol.

EXAMPLE 6

[0065] t-Butyl cholate was prepared according to the process disclosedin Korean Patent No. 2000-59422. 79.0 g (0.17 mol) of t-butyl cholateand 20 g (0.2 mol) of triethylamine were dissolved in 30 g of purifiedtetrahydrofuran, and the solution was transferred into a 100 ml flask.

[0066] 18.0 g (0.17 mol) of acryloyl chloride was slowly added dropwiseto the solution, and the reactants were stirred at ambient temperaturefor 6 hours. After the reaction ended, amine salt produced during thereaction was removed using a glass filter, and the reaction mass wasprocessed by column chromatography to yield an acryl-based compoundhaving a t-butyl cholate group.

[0067] 50.0 g (0.094 mol) of the above-obtained compound was dissolvedin 200 ml of methylene chloride, and the solution was transferred into aflask, and 150 ml of trifluoroacetic acid was slowly added using adropping funnel while keeping the solution temperature at 0° C. by meansof an ice bath, then the solution was stirred at 0° C. for 2 hours.After the reaction ended, the solution was neutralized with sodiumbicarbonate, and then the product was extracted from the reactionmixture by using methylene chloride and water. The extract was processedby column chromatography to yield a compound of formula 13:

EXAMPLE 7

[0068] The monomer of formula 8 obtained in Example 1 and a monomer offormula 13 obtained in Example 6 were dissolved in tetrahydrofuran. Thesolution, together with 2,2′-azobisisobutyronitrile as a polymerizinginitiator, was introduced into an ampoule for polymerization, and thereactants were processed at 60° C. for 6 hours to be polymerized. Afterthe reaction, the reactants were precipitated in petroleum ether, andthe solid mass recovered was dried under reduced pressure to yield acompound of formula 14:

[0069] wherein, a is 0.32, and b is 0.68;

[0070] n (the degree of polymerization) is 140; and

[0071] R₅ represents the following structure:

EXAMPLE 8

[0072] The monomer of formula 9 obtained in Example 2, the monomer offormula 13 obtained in Example 6, and 2-hydroxyethylacrylate weredissolved in tetrahydrofuran, and then the same process as in Example 7was carried out to yield a compound of formula 15:

[0073] wherein, a is 0.35, b is 0.54, and c is 0.11;

[0074] n (the degree of polymerization) is 154; and

[0075] R₅ represents the same structure as defined above.

EXAMPLE 9

[0076] The monomer of formula 10 obtained in Example 3, the monomer offormula 13 obtained in Example 6, and 2-hydroxyethylacrylate weredissolved in tetrahydrofuran, and then the same process as in Example 7was carried out to yield a compound of formula 16:

[0077] wherein, a is 0.31, b is 0.56, and c is 0.13;

[0078] n (the degree of polymerization) is 171; and

[0079] R₅ represents the same structure as defined above.

EXAMPLE 10

[0080] The monomer of formula 11 obtained in Example 4, the monomer offormula 13 obtained in Example 6, 2-hydroxyethylacrylate, and acrylicacid were dissolved in tetrahydrofuran, and then the same process as inExample 7 was carried out to yield a compound of formula 17:

[0081] wherein, a is 0.32, b is 0.51, c is 0.12, and d is 0.05;

[0082] n (the degree of polymerization) is 137; and

[0083] R₅ represents the same structure as defined above.

EXAMPLE 11

[0084] The monomer of formula 12 obtained in Example 5, the monomer offormula 13 obtained in Example 6, 2-hydroxyethylacrylate, and acrylicacid were dissolved in tetrahydrofuran, and then the same process as inExample 7 was carried out to yield a compound of formula 18:

[0085] wherein, a is 0.33, b is 0.48, c is 0.13, and d is 0.06;

[0086] n (the degree of polymerization) is 128;

[0087] R₅ represents the same structure as defined above.

EXAMPLE 12

[0088] The monomer of formula 8 obtained in Example 1 was dissolved intetrahydrofuran, and then the same process as in Example 7 was carriedout to yield a homopolymer of formula 19:

[0089] wherein, n (the degree of polymerization) is 188.

EXAMPLE 13

[0090] The monomer of formula 10 obtained in Example 3 was dissolved intetrahydrofuran, and then the same process as in Example 7 was carriedout to yield a homopolymer of formula 20:

[0091] wherein, n (the degree of polymerizaiton) is of 197.

EXAMPLE 14

[0092] The monomer of formula 13 obtained in Example 6 was dissolved intetrahydrofuran, and then the same process as in Example 7 was carriedout to yield a homopolymer of formula 21:

[0093] wherein, n (the degree of polymerization) is 114; and

[0094] R₅ represents the same structure as defined above.

EXAMPLE 15

[0095] In a laboratory that is isolated from extreme UV radiation, 0.2 gof the compound of formula 14 prepared in Example 7 and 0.004 g oftriphenylsulfonium triplate as a photoacid generator were dissolved in1.2 g of propylene glycol monomethylether acetate, and then filtered twotimes with a syringe filter to yield a photoresist composition.

EXAMPLE 16

[0096] A photoresist composition was prepared by the same procedure asin Example 15 except that 0.2 g of the compound of formula 15 preparedin Example 8 was used.

EXAMPLE 17

[0097] A photoresist composition was prepared by the same procedure asin Example 15 except that 0.2 g of the compound of formula 16 preparedin Example 9 was used.

EXAMPLE 18

[0098] A photoresist composition was prepared by the same procedure asin Example 15 except that 0.2 g of the compound of formula 17 preparedin Example 10 was used.

EXAMPLE 19

[0099] A photoresist composition was prepared by the same procedure asin Example 15 except that 0.2 g of the compound of formula 18 preparedin Example 11 was used.

EXAMPLE 20

[0100] A photoresist composition was prepared by the same procedure asin Example 15 except that 0.06 g of the compound of formula 19 preparedin Example 12 and 0.14 g of the compound of formula 21 prepared inExample 14 were used.

EXAMPLE 21

[0101] A photoresist composition was prepared by the same procedure asin Example 15 except that 0.06 g of the compound of formula 20 preparedin Example 13 and 0.14 g of the compound of formula 21 prepared inExample 14 were used.

APPLICATION EXAMPLE 1

[0102] After hexamethyldisilazane solution was applied dropwise onto asilicon wafer, the silicon wafer was spin-coated at 1,500 rpm for 30seconds, then it was pretreated by heating at 110° C. for 90 secondswith a hot-plate. The photoresist composition obtained in Example 15 wasapplied dropwise onto the pretreated silicon wafer, the silicon waferwas spin-coated at 2,000 rpm for 60 seconds, and then it was pre-bakedfor 90 seconds on a hot-plate at 100° C. to form a thin film. After thethus-formed thin film was irradiated at 17 mJ/cm² of exposure with a UVirradiator, it was post-baked for 120 seconds on a hot-plate at 120° C.The post-baked wafer was dipped in a 2.38% by weight aqueous solution oftetramethylammonium hydroxide used as a developer for 120 seconds,whereby a negative image with a 0.5 μm resolution (pattern of 0.5 μmwidth) was obtained.

APPLICATION EXAMPLE 2

[0103] After pretreatment of a silicon wafer in the same manner as inApplication Example 1, the photoresist composition obtained in Example16 was applied dropwise onto the pretreated silicon wafer, the siliconwafer was spin-coated at 2,000 rpm for 60 seconds, and then it waspre-baked for 90 seconds on a hot-plate at 100° C. to form a thin film.After the thus-formed thin film was irradiated at 23 mJ/cm² of exposurewith a UV irradiator, it was post-baked for 120 seconds on a hot-plateat 120° C. The post-baked wafer was dipped in a 2.38% by weight aqueoussolution of tetramethylammonium hydroxide used as a developer for 90seconds, whereby a negative image with a 0.5 μm resolution was obtained.

APPLICATION EXAMPLE 3

[0104] After pretreatment of a silicon wafer in the same manner as inApplication Example 1, the photoresist composition obtained in Example17 was applied dropwise onto the pretreated silicon wafer, the siliconwafer was spin-coated at 2,000 rpm for 60 seconds, and then it waspre-baked for 90 seconds on a hot-plate at 100° C. to form a thin film.After the thus-formed thin film was irradiated at 25 mJ/cm² of exposurewith a UV irradiator, it was post-baked for 120 seconds on a hot-plateat 120° C. The post-baked wafer was dipped in a 2.38% by weight aqueoussolution of tetramethylammonium hydroxide used as a developer for 90seconds, whereby a negative image with a 0.5 μm resolution was obtained.

APPLICATION EXAMPLE 4

[0105] After pretreatment of a silicon wafer in the same manner as inApplication Example 1, the photoresist composition obtained in Example18 was applied dropwise onto the pretreated silicon wafer, the siliconwafer was spin-coated at 2,000 rpm for 60 seconds, and then it waspre-baked for 90 seconds on a hot-plate at 100° C. to form a thin film.After the thus-formed thin film was irradiated at 30 mJ/cm² of exposurewith a UV irradiator, it was post-baked for 120 seconds on a hot-plateat 130° C. The post-baked wafer was dipped in a 2.38% by weight aqueoussolution of tetramethylammonium hydroxide used as a developer for 90seconds, whereby a negative image with a 0.5 μm resolution was obtained.

APPLICATION EXAMPLE 5

[0106] After pretreatment of a silicon wafer in the same manner as inApplication Example 1, the photoresist composition obtained in Example19 was applied dropwise onto the pretreated silicon wafer, the siliconwafer was spin-coated at 2,000 rpm for 60 seconds, and then it waspre-baked for 90 seconds on a hot-plate at 100° C. to form a thin film.After the thus-formed thin film was irradiated at 30 mJ/cm² of exposurewith a UV irradiator, it was post-baked for 120 seconds on a hot-plateat 130° C. The post-baked wafer was dipped in a 2.38% by weight aqueoussolution of tetramethylammonium hydroxide used as a developer for 90seconds, whereby a negative image with a 0.5 μm resolution was obtained.

APPLICATION EXAMPLE 6

[0107] After pretreatment of a silicon wafer in the same manner as inApplication Example 1, the photoresist composition obtained in Example20 was applied dropwise onto the pretreated silicon wafer, the siliconwafer was spin-coated at 2,000 rpm for 60 seconds, and then it waspre-baked for 90 seconds on a hot-plate at 100° C. to form a thin film.After the thus-formed thin film was irradiated at 20 mJ/cm² of exposurewith a UV irradiator, it was post-baked for 120 seconds on a hot-plateat 130° C. The post-baked wafer was dipped in a 2.38% by weight aqueoussolution of tetramethylammonium hydroxide used as a developer for 90seconds, whereby a negative image with a 0.5 μm resolution was obtained.

APPLICATION EXAMPLE 7

[0108] After pretreatment of a silicon wafer in the same manner as inApplication Example 1, the photoresist composition obtained in Example21 was applied dropwise onto the pretreated silicon wafer, the siliconwafer was spin-coated at 2,000 rpm for 60 seconds, and then it waspre-baked for 90 seconds on a hot-plate at 100° C. to form a thin film.After the thus-formed thin film was irradiated at 27 mJ/cm² of exposurewith a UV irradiator, it was post-baked for 120 seconds on a hot-plateat 130° C. The post-baked wafer was dipped in a 2.38% by weight aqueoussolution of tetramethylammonium hydroxide used as a developer for 90seconds, whereby a negative image with a 0.5 μm resolution was obtained.

[0109] When a photoresist composition is made using the polymeraccording to the present invention, a high degree of cross linking ofthe photoresist composition brings about a big difference in solubilitytoward a developing agent between the exposed portion and the unexposedportion, and thus negative patterns of high sensitivity can be obtained.In addition, since no swelling of the photoresist appears during thedeveloping process, unlike conventional negative photoresists, highresolution patterns with superior shapes can be obtained.

What is claimed is:
 1. A monomer for a chemically amplified negativephotoresist, which is represented by the formula 1 or 2:

wherein: R₁ is H or CH₃; R₂ and R₄ are each independently selected from(R)_(α)(CH₂)_(β)R′ and (R)_(α)[(CH₂)_(γ)O]_(δ)R′ (wherein R is CO, CO₂,O, OCO, or OCO₂, R′ is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1or 2, and δ is 1 to 5); R₃ is represented by one of the formula:

wherein R₆, which combines an acetal compound and a vinyl compound, is aC₁-C₅ saturated alkyl, a C₁-C₅ ether, or a C₁-C₅ carbonyl; R₃ to R₇ areeach independently selected from H, C₁-C₅ saturated alkyls, C₁-C₅ethers, C₁-C₅ carbonyl groups, and C₁-C₅ alcohol groups; and m is anumber ranging from 1-5; and R₅ is represented by the formula:

wherein R₁₂ and R₁₃ are identical or each independently H or OH; and *represents the bonding site at which the R₄ group is bonded.
 2. Themonomer for a chemically amplified negative photoresist according toclaim 1 wherein: R₁ is H; R₂ is CO₂; R₃ is

R₄ is CO₂; and R₅ is


3. A polymer for a chemically amplified negative photoresist, which isrepresented by formula 5:

wherein R₁ is H or CH₃; R₂ and R₄ are each independently selected from(R)_(α)(CH₂)_(β)R′ and (R)_(α [(CH) ₂)_(γ)O]_(δ)R′ (wherein, R is CO,C₂, O, OCO, or OCO₂, R′ is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γis 1 or 2, and δ is 1 to 5); R₃ is represented by one of the formula:

wherein R₆, which combines an acetal compound and a vinyl compound, is aC₁-C₅ saturated alkyl, a C₁-C₅ ether, or a C₁-C₅ carbonyl; R₇ to R₁₁ areeach independently selected from H, C₁-C₅ saturated alkyls, C₁-C₅ethers, C₁-C₅ carbonyl groups, C₁-C₅ alcohol groups; and m is a numberranging from 1-5; and R₅ is represented by formula:

wherein R₁₂ and R₁₃ are each independently selected from H and OH, and *represents the bonding site at which the R₄ group is bonded; R₁₄ and R₁₆are each independently selected from a single bond, (R)_(α)(CH₂)_(β)R′and (R)_(α)[(CH₂)_(γ)O]_(δ)R′ (wherein R is CO, CO₂, O, OCO, or OCO₂, R′is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1 or 2, and δ is 1 to5); R₁₅ is a hydroxyl group; R₁₇ is a carboxyl group; a, b, c, and drepresent mole ratios of each monomer, a has a value of 0-0.5, b has avalue of 0-0.9, c has a value of 0-0.3, and d has a value of 0-0.3,provided that a+b+c+d=1; and n represents the degree of polymerizationof each polymer, and has a value of at least
 2. 4. The polymer for achemically amplified negative photoresist according to claim 3 wherein:R₁ is H; R₂ is CO₂; R₃ is

R₄ is CO₂; R₅ is

R₁₄ is CO₂CH₂CH₂, R₁₅ is OH, R₁₆ is a single bond, and R₁₇ is COOH.
 5. Achemically amplified negative photoresist composition comprising: aphotoacid generator; and a homopolymer of the formula 6, a homopolymerof the formula 7, or a combination thereof;

wherein R₁ is H or CH₃; R₂ and R₄ are each independently selected from(R)_(α)(CH₂)_(β)R′ and (R)_(α)[(CH₂)_(γ)O]_(δ)R′ (wherein R is CO, CO₂,O, OCO, or OCO₂, R′ is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1or 2, and δ is 1 to 5); R₃ is represented by one of the formula:

wherein R₆, which combines an acetal compound and a vinyl compound, is aC₁-C₅ saturated alkyl, a C₁-C₅ ether, or a C₁-C₅ carbonyl; R₇ to R₁₁ areeach independently selected from H, C₁-C₅ saturated alkyls, C₁-C₅ethers, C₁-C₅ carbonyl groups, and C₁-C₅ alcohol groups; and m is anumber ranging from 1-5; and R₅ is represented by the formula:

wherein R₁₂ and R₁₃ are each independently H or OH; * represents thebonding site at which the R₄ group is bonded; and n represents thedegree of polymerization of each polymer, and has a value of at least 2.6. The chemically amplified negative photoresist composition accordingto claim 5 wherein the photoresist composition comprises a combinationof the homopolymer of the formula 6 and the homopolymer of the formula7.
 7. The composition for a chemically amplified negative photoresistaccording to claim 5 wherein: R₁ is H; R₂ is CO₂; R₃ is

R₄ is CO₂; R₅ is

R₁₄ is CO₂CH₂CH₂, R₁₅ is OH, R₁₆ is a single bond, and R₁₇ is COOH. 8.The chemically amplified negative photoresist composition according toclaim 5 wherein the photoresist composition comprises 10 to 20 wt. % ofthe polymer and 0.1 to 1.0 wt. % of the photoacid generator based on theweight of the photoresist.
 9. A chemically amplified negativephotoresist composition comprising; a photoacid generator; and a polymerof formula 5:

wherein R₁ is H or CH₃; R₂ and R₄ are each independently selected from(R)_(α)(CH₂)_(β)R′ and (R)_(α)[(CH₂)_(γ)O]_(δ)R′ (wherein, R is CO, CO₂,O, OCO, or OCO₂, R′ is O, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1or 2, and δ is 1 to 5); R₃ is represented by one of the formula:

wherein R₆, which combines an acetal compound and a vinyl compound, is aC₁-C₅ saturated alkyl, a C₁-C₅ ether, or a C₁-C₅ carbonyl; R₇ to R₁₁ areeach independently selected from H, C₁-C₅ saturated alkyls, C₁-C₅ethers, C₁-C₅ carbonyl groups, and C₁-C₅ alcohol groups; and m is anumber ranging from 1-5; and R₅ is represented by the formula:

wherein R₁₂ and R₁₃ are each independently H or OH; and * represents thebonding site at which the R₄ group is bonded; R₁₄ and R₁₆ are eachindependently selected from a single bond, (R)_(α)(CH₂)_(β)R′ and(R)_(α)[(CH₂)_(γ)O]_(δ)R′ (wherein R is CO, CO₂, O, OCO, or OCO₂, R′ isO, CO₂, or OCO₂, α is 0 or 1, β is 0 to 5, γ is 1 or 2, and δ is 1 to5); R₁₅ is a hydroxyl group; R₁₇ is a carboxyl group; a, b, c, and drepresent the mole ratios of each monomer, wherein a has a value of0-0.5, b has a value of 0-0.9, c has a value of 0-0.3, and d has a valueof 0-0.3, provided that a+b+c+d=1; and n represents the degree ofpolymerization of each polymer, and has a value of at least
 2. 10. Thechemically amplified negative photoresist composition according to claim9 wherein R₁ is H; R₂ is CO₂; R₃ is

R₄ CO₂; R₅ is

R₁₄ is CO₂CH₂CH₂, R₁₅ is OH, R₁₆ is a single bond, and R₁₇ is COOH. 11.The chemically amplified negative photoresist composition according toclaim 9 wherein the photoresist composition comprises 10 to 20 wt. % ofsaid polymer and 0.1 to 1.0 wt. % of said photoacid generator.